A typical gas discharge laser may employ a pair of spaced apart, elongated discharge electrodes to initiate lasing in a gaseous material. In one arrangement, aluminum, two-piece chamber housing is employed that envelops the gaseous gain media and the discharge region. In addition to containing the gain media, the housing typically acts as a mechanical support for the electrodes, and in some cases, an insulator which electrically separates at least one of the electrodes from the housing (which is typically grounded). Thus, the housing is required to be relatively stiff and rigid. For the case where the insulator, which is typically made of a relatively brittle ceramic, is mechanically coupled to the housing, deformation of the housing can place stresses on the insulator which can cause the insulator to flex, and in severe cases, crack. In addition to stresses from the housing, the insulator may also be subjected to stresses from thermal loading as well as thermal gradients produced by electrical tracking, a phenomenon known to occur in high power excimer discharge lasers.
For some types of lasers, e.g. pulsed excimer lasers, pulse energy can be increased by increasing the pressure of the gaseous gain media. This pressure, in turn, places additional stresses on the chamber housing which act to deform the housing. Moreover, the wall of the housing is typically formed with one or more through-holes to allow electrical conductors to pass to one of the electrodes. These holes can create a weakened region of the housing near the insulator which is particularly vulnerable to deformation. One way to provide a stiffer housing would be to make it out of a stronger material, e.g., steel, however this may result in an undesirable increase in weight and cost.
With the above considerations in mind, Applicants disclose a chamber for a high energy excimer laser source.